Apparatus for displaying base lines used for a characeristic display

ABSTRACT

An apparatus for displaying base lines used for a characteristic display device indicating a a pattern on a display screen by displaying relative information of the abscissa and of the ordinate, in which a first gate is provided for selecting alternately at regular intervals the reference level of the information of the abscissa and an ordinate-base-line signal having a gentle slope at least at either the start or the end of the wave form thereof, and a second gate is provided for selecting, in a period in which the first gate selects the reference level of the information of the abscissa, an abscissabase-line signal having a wave form similar to the ordinate-baseline signal and for selecting, in a period in which the first gate selects the ordinate-base-line signal, the reference level of the information of the ordinate. The outputs of the first gate and the second gate are respectively applied to the horizontal input and the vertical input of the characteristic display at frequently interrupted intervals of the relative information of the abscissa and of the ordinate.

United States Patent 51 3,681,647

Nakagawa [4 1 Aug. 1, 1972 [5 APPARATUS FOR DISPLAYING BASE Primary Examiner-Carl D. Quarforth LINES USED FOR A CHARACTERISTIC Assistant Examiner-J. M. Potenza DISPLAY Attorney-Robert E. Burns and Emmanuel J. Lobato [72] Inventor: Toshiya Nakagawa, Tokyo-to, Japan [57] ABSTRACT Assign; lwasaki Tsushinkixabushiki lfaisha An apparatus for displaying base lines used for a klmw" as lwats" Elecmc characteristic display device indicating a a pattern on -L Tokyo-t0, Japan a display screen by displaying relative information of I 1 the abscissa and of the ordinate, in which a first gate is [22] Filed Aug 969 provided for selecting alternately at regular intervals [21]" App1.No.: 848,529 the reference level of the information of the abscissa 7 n and an ordinate-base-line signal having a gentle slope at least at either the start or the end of the wave form [30] Forelgn Apphcatlon Prwmy Dam thereof, and a second gate is provided for selecting, in Aug. 14, 1968 Japan ..43/5735O a period in which the first gate selects the reference level of the information of the abscissa, an abscissa- [52] U.S. Cl ..315/l8, 315/23 base-line signal having a wave form Similar to the 51 Int. Cl ..H0lj 29/70 dinate-base-line signal and for selecting, in a Period in [58 Field of Search ..315/18, 23, 26; 340/324 A; which the first gate Selects the ordinate-baseline 235/198 signal, the reference level of the information of the ordinate. The outputs of the first gate and the second 7 gate are respectively applied to the horizontal input [56] References Cited and the vertical input of the characteristic display at UNlTED STATES TENT frequently interrupted intervals of the relative information of the abscissa and of the ordinate. 2,539,971 1/1951 POtjfil ..315/18 X 2,548,276 4/1951 Weisbecker ..315/18 X 3 Claims, 7 Drawing Figures 3,404,309 10/1968 Massell et al. ..3l5/l8 Va T! I 5 VI?! 1 6, /GJ A3 5- GATE AMPLI- GATE CIRCUIT PIER 152 s f *AMPLIFIER CR7 1 l 3 Al I A2 4 A4 1 9 '1 I AMPLI- GATE fins/Pu- F/ER cmcu/r FIER i I V1 5' GATE 1 Vt MTASTABLE J CIRCUIT Mum VIBRATUR vRs T/L l 86 BISTABLE CIRCUIT PATENTEDAuc 1 I972 3.681.647

SHEEY 1 BF 3 Va T! I 6/ 63 A3 3 ,vb GATE fVa AMP GATE CIRCUIT FIER T RCUIT u VR VR L ags Z55 CRT H E AMPLIFIER A A4 f 2 5 I 1 AMPLI- q- GATE v AMPLI- CIRCUIT FIER 5 VC ;I I

GATE P M ASTABLE CIRCUIT f Mumware/awn vR5 F1 q. 1 BC BISTABLE CIRCUIT PATENTEDAUB I I972 sum 3 or 5 Fig. 5A

Fig. 5C vbTmE Hg. 5 B VOLT?? APPARATUS FOR DISPLAYING BASE LINES USED FOR A CHARACTERISTIC DISPLAY This invention relates to apparatus for displaying base lines and more particularly to apparatus for displaying base lines on the screen of a characteristic display device for displaying a characteristic of a sample, such as a semiconductor, etc.

In such a characteristic display, base lines representative of reference lines such as a level of zero current or of zero voltage are necessary. In conventional display devices the base lines are indicated by providing in front of the screen a transparent plate'having lines corresponding to the base lines, or, by displaying the base lines only in response to manual operation of a push button etc. In the former case, the relative position between the characteristic pattern displayed on the screen (e.g., the display screen of a cathode-ray tube) and the lines on the transparent plate will deviate from their correct positions. This has disadvantages such as erroneous observation of the characteristic pattern of a sample. In the later case, the characteristic pattern of a sample cannot be displayed on the screen during the display period of the base lines. Consequently, the conventional apparatus for displaying base lines a disadvantage as inconvenience to handle.

An object of this invention is to provide apparatus for displaying base lines capable of displaying in a time shared basis which is observed is simultaneous displaying, the characteristic pattern of a sample together with the base lines on the screen of a characteristic display device.

The principle of this invention will be better understood from the following more detailed discussion taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a block diagram for illustrating an embodiment of this invention;

FIG. 2 is a block diagram illustrating another embodiment of this invention;

FIG. 3 are time charts illustrating wave forms explanatory of the operation of the embodiments shown in FIGS. 1 and 2;

FIG. 4 is an example of a characteristic pattern and base lines displayed in accordance with this invention; and

FIGS. 5A, 5B, and 5C are other examples of characteristic patterns and base lines displayed in accordance with this invention.

With reference to FIG. 1, an example of this invention will be described. In this example, an alternating current supplied from an alternating current source S is adjusted to an appropriate voltage at an adjustable transformer T The output of the transformer T is rectified by a rectifier D, and the half wave output rectified is applied to a sample SA through a resistor R, and a resistor R A current flowing through the sample SA is converted to a voltage at the resistor R This voltage is amplified at an amplifier A so that a current signal e, is obtained at the output of the amplifier A A voltage across the sample SA is adjusted to an appropriate voltage by a differential attenuator composed of resistors R and R and amplified at a differential amplifier A,, so that a voltage signal e, is obtained at the output of the amplifier A On the other hand, an astable multivibrator MUL excites a bistable circuit BC, the output v, of the bista ble circuit BC as shown in FIG. 3 is applied to a gate G, and gate G The alternating-current supplied from the alternating source S is applied to the gate G, through a transformer T, and a variable resistor VR, as an abscissa-base-line signal. Moreover, the reference level of the current signal 0.- is applied to the gate G, from a variable resistor VR3. The gate G. switches the abscissabase-line signal and the reference level of the current signal 2, by the use of the output Va of the bistable circuit BC, so that a horizontal-base-line signal 1 1, is obtained at the output of the gate G1. On the other hand,

the alternating current supplied from the alternating source S is applied to the gate G2 through a transformer T and a variable resistor VR4 as an ordinate-base-line signal. Moreover, the reference level of the voltage signal 2, is applied to the gate G; from a variable resistor VR6. The gate G2 switches the ordinate-baseline signal and the reference level of the voltage signal ev by the use of the output 11., of the bistable circuit BC, so that a vertical-base-line signal v is obtained at the output of the gate G2. In this case, the switching periods of the gates G1 and G2 are so determined that when the gate G1 selects the abscissa-base-line signal the gate G2 selects the reference level of the voltage signal e (i.e., the output of the variable resistor VRG) and that when the gate G1 selects the reference level of the current signal e (i.e., the output of the variable resistor VR the gate G2 selects the ordinatebase-line signal (i.e., the output of the variable resistor wi The output v,,, of the astable multivibrator MUL is applied to both a gate G and a gate G as respective control signals, so that the gate circuit G switches the voltage signal e,, and the horizontal-base-line signal v so as to obtain a signal v and so that the gate G switches the current signal e, and the vertical-base-line signal v so as to obtain a signal v,.

The signals v and v, are respectively amplified by a horizontal amplifier A and a vertical amplifier A and applied to horizontal terminals and vertical terminals of a cathode-ray tube CRT respectively, Accordingly, the characteristic pattern of the sample SA indicated by the voltage signal e, being the information of the abscissa and the current signal e, being the information of the ordinate are displayed on the screen of the cathode-ray tube CRT together with a dotted abscissa base line and a dotted ordinate base line as shown in FIG. 4 in accordance with a time shared basis. If the repetition frequency of the output v,, of the multivibrator MUL is determined at an appropriately high frequency (e.g., hundred or thousand times the horizontal sweep frequency), the dotted lines on the screen are observed as continuous lines.

As understood from FIG. 3, since the display period of the information of the abscissa and of the ordinate has a duration twice the display period of the base lines, the intensity of the displayed characteristic pattern is twice the intensity of the base lines if the duty cycle of the output of the multivibrator MUL is 50 percent. Therefore, a difference between the intensity of the characteristic pattern and the intensity of the base lines can be voluntarily changed.

The resistors VR and VR are employed for sliding the position of each of the base lines in the directions of the respective base lines, so that the characteristic pattern in only one quadrant or in more than one quadrant, such as in both the first and second quadrants or in both the first and third quadrants etc. can be displayed.

The resistors VR and VR, are employed for adjusting the respective length of the base lines. Moreover, the resistors VR and VR are employed for adjusting the displayed position of the intersection point of the base lines so as to correspond to the original beam spot which appears at no horizontal input and no vertical input for the cathode-ray tube CRT.

FIG. 2 shows another embodiment of this invention, in which a direct current reference "voltage is further applied to the sample SA by a direct-current source E. In this case, if a direct current voltage equal to the direct-current reference voltage is applied to the sample SA, the beam spot is not shifted in the horizontal direction and the vertical base line is displayed at this position.

As mentioned above, if a direct current bias voltage is applied to the sample SA, the starting point of the characteristic pattern and the vertical base line do not correspond to each other as shown in FIGS. A and 5B. In these cases, the display of the base lines is effective to observe correctly the characteristic pattern. This merit of displaying the base lines will be clearly understood from the fact that the start of the characteristic pattern do not correspond to a point of zero voltage and of zero current if another source supplies power to the sample SA in the embodiment shown in FIG. 1, or, the fact that if the sample SA is excited by a sinusoidal wave instead of the rectified half-wave the zero point is not distinctive as shown in FIG. 5C.

In each of the embodiments shown in FIGS. 1 and 2, the output v,, of the multivibrator MUL and the output v of the bistable circuit BC can be replaced by each other. In the above mentioned embodiments, the baseline signal is a sinusoidal wave supplied from the alternating source S to the transformers T and T However, other wave forms can be adopted if they have a gentle slope at least one of the start (level-increasing period) and the end (level-decreasing period) of the wave form, such as triangular wave or saw-tooth wave. Moreover, the switching period of the gates G and G is not necessary to synchronize with the switching period of the gates G and 6,. Therefore, two astable multivibrators can be employed instead of the astable multivibrator MUL so that one of them generates the control signal applied to the gates G and G and the other of them generates the control signal applied to the gates G and G As mentioned above, since the apparatus of this invention can in a time shared basis which is observed as simultaneous displaying, display simultaneously the characteristic pattern indicated by the information of the abscissa and of the ordinate together with baselines indicative of the respective reference levels of the information of the abscissa and of the ordinate, effective merits will be accepted if this invention is applied to a characteristic display for any of circuit elements or for any of materials.

What I claim is:

1. An apparatus for displaying base lines used for a characteristic display device indicating a characteristic pattern on a display screen during selected sweep periods by relative information of the abscissa and of the ordinate, comprising:

a first gate for selecting alternately at regular intervals shorter than sweep periods of the apparatus a reference level of information of the abscissa and an ordinate-base-line signal having a gentle slope at at least either the start or the end of the wave form thereof;

a second gate for selecting, in a period in which the first gate selects the reference level of the information of the abscissa, an abscissa-base-line signal having a wave form similar to the ordinate-baseline signal and for selecting, in. a period in which the first gate selects the ordinate-base-line signal, the reference level of information of the ordinate;

a third gate for switching alternately at regular intervals the information of the abscissa and the output of the first gate;

a fourth gate for selecting, in a period in which the third gate selects the information of the abscissa, the information of the ordinate and for selecting, in a period in which the third gate selects the output of the first gate, the output of the second gate; and

means for applying the output of the third gate and the output of the fourth gate to the horizontal input of the display and the vertical input of the display respectively,

whereby the characteristic pattern and the base lines for the abscissa and the ordinate are simultaneously displayed on the screen of the display device.

2. An apparatus as set forth in claim 1, including means synchronizing selecting operations of the first gate and of the second gate with selecting operations of the third gate and of the fourth gate.

3. An apparatus for displaying base lines used for a characteristic display device indicating a characteristic pattern on a display screen by relative information of the abscissa and of the ordinate, comprising:

a first gate for selecting alternately at regular intervals a reference level of information of the abscissa and an ordinate-base-line signal having a gentle slope at at least either the start or the end of the wave form thereof;

a second gate for selecting, in a period in which the first gate selects the reference level of the information of the abscissa, an abscissa-base-line signal having a wave form similar to the ordinate-baseline signal and for selecting, in a period in which the first gate selects the ordinate-base-line signal, the reference level of information of the ordinate;

a third gate for switching alternately at regular intervals the information of the abscissa and the output of the first gate;

a fourth gate for selecting, in a period in which the third gate selects the information of the abscissa, the information of the ordinate and for selecting, in a period in which the third gate selects the output of the first gate, the output of the second gate;

means for applying the output of the third gate and the output of the fourth gate to the horizontal input of the display and the vertical input of the display respectively, means synchronizing selecting operations of the first gate and of the second fourth gates, and means developing the last-mentioned control signals. whereby the characteristic pattern and the base lines for the abscissa and the ordinate are simultaneously displayed on the screen of the display device. 

1. An apparatus for displaying base lines used for a characteristic display device indicating a characteristic pattern on a display screen during selected sweep periods by relative information of the abscissa and of the ordinate, comprising: a first gate for selecting alternately at regular intervals shorter than sweep periods of the apparatus a reference level of information of the abscissa and an ordinate-base-line signal having a gentle slope at at least either the start or the end of the wave form thereof; a second gate for selecting, in a period in which the first gate selects the reference level of the information of the abscissa, an abscissa-base-line signal having a wave form similar to the ordinate-base-line signal and for selecting, in a period in which the first gate selects the ordinate-base-line signal, the reference level of information of the ordinate; a third gate for switching alternately at regular intervals the information of the abscissa and the output of the first gate; a fourth gate for selecting, in a period in which the third gate selects the information of the abscissa, the information of the ordinate and for selecting, in a period in which the third gate selects the output of the first gate, the output of the second gate; and means for applying the output of the third gate and the output of the fourth gate to the horizontal input of the display and the vertical input of the display respectively, whereby the characteristic pattern and the base lines for the abscissa and the ordinate are simultaneously displayed on the screen of the display device.
 2. An apparatus as set forth in claim 1, including means synchronizing selecting operations of the first gate and of the second gate with selecting operations of the third gate and of the fourth gate.
 3. An apparatus for displaying base lines used for a characteristic display device indicating a characteristic pattern on a display screen by relative information of the abscissa and of the ordinate, comprising: a first gate for selecting alternately at regular intervals a reference level of information of the abscissa and an ordinate-base-line signal having a gentle slope at at least either the start or the end of the wave form thereof; a second gate for selecting, in a period in which the first gate selects the reference level of the information of the abscissa, an abscissa-base-line signal having a wave form similar to the ordinate-base-line signal and for selecting, in a period in which the first gate selects the ordinate-base-line signal, the reference level of information of the ordinate; a third gate for switching alternately at regular intervals the information of the abscissa and the output of the first gate; a fourth gate for selecting, in a period in which the third gate selects the information of the abscissa, the information of the ordinate and for selecting, in a period in which the third gate selects the output of the first gate, the output of the second gate; means for applying the output of the third gate and the output of the fourth gate to the horizontal input of the display and the vertical input of the display respectively, means synchronizing selecting operations of the first gate and of the second gate with selecting operations of the third gate and of the fourth gate, means developing a control signal for performing the selecting operations of the first and second gates having a frequency equal to half the frequency of a control signal for performing the selecting operations of the third and fourth gates, and means developing the last-mentioned control signals, whereby the characteristic patterN and the base lines for the abscissa and the ordinate are simultaneously displayed on the screen of the display device. 